Blaskowitz commanded Eighth Army in the September 1939 German invasion of Poland, with the task of protecting Tenth Army's northern flank during the drive on Warsaw. Following initial German success, the Poles counterattacked on 9 September against the flank of the Eighth Army and managed to destroy one of Blaskowitz's five infantry divisions before they were defeated, with Tenth Army's assistance. The Battle of Kutno was the biggest Polish victory of the campaign.
On 23 October 1939, Blaskowitz was made commander of German forces occupying Poland. An officer of the old school who set high standards for his men, he was shocked by the brutal actions of the Schutzstaffel (SS) against the local population. Blaskowitz went so far as to draw up a memorandum protesting these actions, which earned him Adolf Hitler's distrust.
Blaskowitz briefly commanded Ninth Army in the invasion of France between May and June 1940 and then was the military governor of northern France before being assigned to command the First Army stationed in France in October 1940. Blaskowitz remained in this position until 10 May 1944, when he was assigned command of Army Group G, defending the Mediterranean and South Atlantic French coasts. In Operation dragoon in August 1944, the Allies invaded the French Riveria and easily pushed aside Blaskowitz's thinly spread forces. Relieved of his command in September 1944, he returned to command Army Group H in Holland in January 1945, where he demonstrated compassion for the Dutch by permitting them medical supplies and food during the Allied advance.
Captured on 8 May 1945 by Canadian forces, Blaskowitz was charged with war crimes that involved passing along Hitler's order regarding the execution of enemy commandos. Rather than face trial, he committed suicide on 5 February 1948 in Nuremberg, Germany. Some believe he was murdered to prevent him from revealing SS secrets.
Giziowski, Richard. The Enigma of General Blaskowitz. New York: Hippocrene Books, 1997.; Wilt, Alan F. The French Riviera Campaign of August 1944. Cardondale: Southern Illinois University Press, 1981.